The document describes a Product Design Sprint, which is a 5-phase exercise that uses design thinking to reduce risks in bringing products to market. The 5 phases are: Day 1) understand the design problem through research; Day 2) diverge and develop solutions; Day 3) decide on the best ideas; Day 4) prototype a quick solution; Day 5) validate the prototype with users outside the company. The goal of the Sprint is to quickly build something when a lot is unknown in order to find product/market fit and reduce risks before fully developing or releasing a product.